1 files changed, 25 insertions, 11 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
index e945195b24c9..58522195081b 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
@@ -42,6 +42,8 @@ void test_ringbuf_multi(void)
 {
 	struct test_ringbuf_multi *skel;
 	struct ring_buffer *ringbuf = NULL;
+	struct ring *ring_old;
+	struct ring *ring;
 	int err;
 	int page_size = getpagesize();
 	int proto_fd = -1;
@@ -50,17 +52,12 @@ void test_ringbuf_multi(void)
 	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
 		return;
 
-	err = bpf_map__set_max_entries(skel->maps.ringbuf1, page_size);
-	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
-		goto cleanup;
-
-	err = bpf_map__set_max_entries(skel->maps.ringbuf2, page_size);
-	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
-		goto cleanup;
-
-	err = bpf_map__set_max_entries(bpf_map__inner_map(skel->maps.ringbuf_arr), page_size);
-	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
-		goto cleanup;
+	/* validate ringbuf size adjustment logic */
+	ASSERT_EQ(bpf_map__max_entries(skel->maps.ringbuf1), page_size, "rb1_size_before");
+	ASSERT_OK(bpf_map__set_max_entries(skel->maps.ringbuf1, page_size + 1), "rb1_resize");
+	ASSERT_EQ(bpf_map__max_entries(skel->maps.ringbuf1), 2 * page_size, "rb1_size_after");
+	ASSERT_OK(bpf_map__set_max_entries(skel->maps.ringbuf1, page_size), "rb1_reset");
+	ASSERT_EQ(bpf_map__max_entries(skel->maps.ringbuf1), page_size, "rb1_size_final");
 
 	proto_fd = bpf_map_create(BPF_MAP_TYPE_RINGBUF, NULL, 0, 0, page_size, NULL);
 	if (CHECK(proto_fd < 0, "bpf_map_create", "bpf_map_create failed\n"))
@@ -77,6 +74,10 @@ void test_ringbuf_multi(void)
 	close(proto_fd);
 	proto_fd = -1;
 
+	/* make sure we can't resize ringbuf after object load */
+	if (!ASSERT_ERR(bpf_map__set_max_entries(skel->maps.ringbuf1, 3 * page_size), "rb1_resize_after_load"))
+		goto cleanup;
+
 	/* only trigger BPF program for current process */
 	skel->bss->pid = getpid();
 
@@ -85,11 +86,24 @@ void test_ringbuf_multi(void)
 	if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n"))
 		goto cleanup;
 
+	/* verify ring_buffer__ring returns expected results */
+	ring = ring_buffer__ring(ringbuf, 0);
+	if (!ASSERT_OK_PTR(ring, "ring_buffer__ring_idx_0"))
+		goto cleanup;
+	ring_old = ring;
+	ring = ring_buffer__ring(ringbuf, 1);
+	ASSERT_ERR_PTR(ring, "ring_buffer__ring_idx_1");
+
 	err = ring_buffer__add(ringbuf, bpf_map__fd(skel->maps.ringbuf2),
 			      process_sample, (void *)(long)2);
 	if (CHECK(err, "ringbuf_add", "failed to add another ring\n"))
 		goto cleanup;
 
+	/* verify adding a new ring didn't invalidate our older pointer */
+	ring = ring_buffer__ring(ringbuf, 0);
+	if (!ASSERT_EQ(ring, ring_old, "ring_buffer__ring_again"))
+		goto cleanup;
+
 	err = test_ringbuf_multi__attach(skel);
 	if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err))
 		goto cleanup;